Method for producing a contact substrate and corresponding contact substrate

ABSTRACT

The invention relates to a method for producing a contact substrate ( 10 ) as well as to a contact substrate with through-plating between a connector arrangement ( 21 ) arranged at the top of a dielectric carrier substrate ( 12 ) and the underside of the carrier substrate, wherein the connector arrangement extends along an aperture margin ( 22 ) of a substrate recess ( 15 ), and the underside ( 11 ) of the carrier substrate ( 12 ) is supported by a backstop ( 23 ), wherein a formed solder material part ( 24 ) is placed in the substrate recess ( 15 ), and in a subsequent method-related step said formed solder material part ( 24 ) is deformed within the substrate recess so as to form a formed contact part ( 50 ), such that radial displacement of the material of the formed solder material part in the substrate recess results in a non-positive connection between an intrados surface ( 28 ) of the substrate recess and the connector arrangement ( 21 ), and that the formed contact part provides through-plating between the connector arrangement ( 21 ) and the underside ( 11 ) of the carrier substrate.

[0001] The invention relates to a method for producing a contactsubstrate with through-plating between a connector arrangement arrangedat the top of a dielectric carrier substrate and the underside of thecarrier substrate, wherein the connector arrangement extends along anaperture margin of a substrate recess, and the underside of the carriersubstrate is supported by a backstop. Furthermore, the invention relatesto a contact substrate with through-plating, comprising a carriersubstrate and a conductor path structure arranged on the carriersubstrate, according to the preambles of claims 12 and 15 respectively.

[0002] Through-plating of the type mentioned above is used toelectrically interconnect connector arrangements which are arranged onopposite sides of a dielectric carrier substrate, or, in the case of asingle-sided arrangement of a connector arrangement on a carriersubstrate, to make possible contacting of the connector arrangement fromthe opposite side, and in this way for example to make possibleplacement of electronic components on both sides of correspondingcontact substrates. Up to now, contact substrates have been used forthis purpose, in which substrates there is already a mechanicallyadhesive bond between the connector arrangement and the carriersubstrate prior to establishing the actual through-plating. As a rule,this means that, by way of contact substrates, substrate carriers areused which in a prior method, which is more or less expensive, have beenprovided with a connector arrangement which is adhesively applied to thesurface of the carrier substrate. For example, photolithographic etchingmethods or chemical deposition methods are well-known for this purpose.

[0003] In order to establish the actual through-plating, an electricallyconductive connection made from a suitable connection material, such asfor example a solder, is created between the connector arrangementsarranged on both sides of the carrier substrate.

[0004] It is the object of the present invention to propose a method forproducing contact substrates as well as to propose a contact substratewhich makes possible simplified manufacture of contact substrates.

[0005] This object is achieved in the method according to the inventionby the characteristics of claim 1.

[0006] In the method according to the invention, a formed soldermaterial part is placed in the substrate recess, and in a subsequentmethod-related step said formed solder material part is deformed withinthe substrate recess so as to form a formed contact part, such thatradial displacement of the material of the formed part in the substraterecess results in a non-positive connection between an intrados surfaceof the substrate recess and the connector arrangement, and so that theformed contact part provides through-plating between the connectorarrangement and the underside of the carrier substrate.

[0007] Implementing the above-mentioned method thus makes possible theproduction of a contact substrate, starting with a carrier substrate anda connector arrangement formed independently of the carrier substrate.The non-positive connection between the carrier substrate and theconnector arrangement by means of the deformed formed contact part notonly makes possible an electrically conductive connection, but at thesame time also a mechanical connection between the connector arrangementand the carrier substrate. The method according to the invention has adecisive advantage in that the production of the contact substratecomprising through-plating does not require prior application of anadhesive connector arrangement to the surface of a substrate carrier.Instead, the mechanical connection of the connector arrangement can becreated concurrently with through-plating.

[0008] In an advantageous variant of the method, displacement takesplace by forming a disc-shaped contact head which protrudes both axiallyand radially beyond the aperture margin of the substrate recess, withthe connector arrangement being accommodated in the region of theaperture margin between the contact head and the top of the carriersubstrate. This makes possible a particularly stable mechanicalconnection, comparable to a so-called “blind rivet connection”.

[0009] In a further advantageous variant of the method, radialdisplacement of the material of the formed solder material part is bymeans of a pressure stamp with a convex contact surface, such that,apart from radial displacement, axial displacement of the materialagainst the direction of pressure of the pressure stamp is caused too.In this process, the volume of the solder material can also be smallerthan the lumen of the substrate recess without the non-positivemechanical connection being negatively affected.

[0010] If furthermore, exposure to pressure takes place by means of apressure stamp which on its contact surface comprises a centeringdevice, displacement becomes possible which is evenly distributed bothradially and axially, i.e. a displacement state becomes possible whichis symmetrical in relation to the center axis of the recess.

[0011] It is also particularly advantageous if in a method-related stepwhich follows the step of forming the formed solder material part into aformed contact part within the substrate recess, the material of theformed part is at least partly re-melted. In this way, the purelynon-positive connection which has been produced by forming the formedbody, which connection in any case makes possible at least temporaryfixation of the connector arrangement to the carrier substrate, can beconverted to a permanent integral fixation. This can in particular beadvantageous in those cases where there are more stringent requirementsconcerning the reliability of the non-positive connection which per seis sufficient to establish a mechanical and electrical connection.

[0012] If re-melting takes place by means of laser energy, re-meltingwhich ranges from a locally defined part right up to complete re-meltingbecomes possible.

[0013] If according to an advantageous variant of the method, prior toplacing the formed solder material part into the substrate recess, asecond connector arrangement is arranged on the underside of the carriersubstrate, between the carrier substrate and the backstop, such that thesecond connector arrangement at least in part forms a bottom of thesubstrate recess, re-melting of the formed contact part makes possible amechanically held and electrically conductive connection betweenconnector arrangements which are arranged on both sides of the carriersubstrate, so that a contact substrate is created which makes possible aswitch-technology connection on both sides of the electronic componentswhich establish contact on the contact substrate.

[0014] An alternative to forming a contact substrate which comprisesconnector arrangements on both sides becomes possible if, prior toplacing the formed solder material part into the substrate recess, onthe underside of the carrier substrate between the substrate and thebackstop a second connector arrangement is arranged, such that thesecond connector arrangement extends along a lower aperture margin ofthe substrate recess.

[0015] If irrespective of the selected variant of the method, prior tore-melting onto the contact head the formed contact part which isarranged in the substrate recess, a further formed solder material partis applied, and subsequently the solder material is, at least in part,re-melted, it is possible at the same time to form through-plating asraised contacts, commonly referred to as “bumps”. In this way,through-plating can for example at the same time be used to form bumpdistributions such as ball grid arrays or similar, which make itpossible, in a particularly simple way, to establish so-called flip chipcontacting of the contact substrates. This re-melting too can be carriedout via laser energy.

[0016] In a first variant, the contact substrate according to theinvention comprises the characteristics of claim 12, and in a furtherindependent variant the characteristics of claim 15.

[0017] In the contact substrate according to the invention, according toclaim 12, an electrically conductive connection between the lowerconnector arrangement and the upper connector arrangement is formed byway of a formed contact part, such that the formed contact partcompletely fills up the substrate recess, and the end of the formedcontact part which end is situated opposite the bottom of the substraterecess comprises a contact head which protrudes beyond the aperturemargin both axially and radially, with said contact head beingnon-positively connected with the upper connector arrangement.

[0018] In the contact substrate constructed according to the invention,through-plating thus not only makes possible an electrically conductiveconnection between the connector arrangements arranged on opposite sidesof the carrier substrate, but also a mechanical connection between theconnector arrangements, said mechanical connection being used for fixingthe connector arrangements on the carrier substrate. Furthermore, due tothrough-plating being made from a formed solder material part, it ispossible, without any further intermediate steps, to use the soldermaterial of the through-plating for producing an integral connectionwith electronic components to be contacted on the contact substrate.

[0019] In order to construct a contact substrate which is made from acarrier substrate compound, it is possible to arrange the lowerconductor path arrangement on a further carrier substrate.

[0020] Through-plating in the contact substrate can be achieved by apurely mechanical forming process, such that the contact head isdisc-shaped and comprises an essentially flat contact surface whichextends parallel to the surface of the carrier substrate.

[0021] Alternatively, through-plating of the contact substrate, whichthrough-plating is formed by formed contact parts, can also be re-meltedafter the mechanical forming process, such that the contact headcomprises a meniscus-shaped raised contact.

[0022] In the further variant according to the invention, as set out inclaim 15, an electrically conductive connection is formed between thelower connector arrangement and the upper connector arrangement, by wayof a formed contact part, such that at its end opposite the bottom ofthe substrate recess the formed contact part comprises a concave contactsurface with an increased contact margin which is connected in anon-positive way with the upper connector arrangement. Due to the raisedcontact margin it is not necessary for the formed contact part tocompletely fill the substrate recess.

[0023] If the second connector arrangement is arranged on a furthercarrier substrate, the contact substrate can also be used for a layersubstrate which comprises several carrier substrate layers.

[0024] Below, preferred embodiments of the method as well as contactsubstrates made according to the method are explained in more detail bymeans of drawings. The following are shown:

[0025]FIG. 1 a carrier substrate arrangement with a double-layerarrangement of carrier substrates comprising connector arrangements;

[0026]FIG. 2 the placement of formed solder material parts in substraterecesses of the carrier substrate arrangement according to FIG. 1 with asubsequent forming process for creating formed contact parts;

[0027]FIG. 3 the placement of further formed solder material parts onthe formed contact parts with a subsequent re-melting process forcreating solder bumps;

[0028]FIG. 4 a first embodiment of a contact substrate;

[0029]FIG. 5 a second embodiment of a contact substrate;

[0030]FIG. 6 the production of a contact substrate with a variant of theformed contact part; and

[0031]FIG. 7 the formed contact part shown in FIG. 6, after a re-meltingprocess.

[0032]FIG. 1 shows a carrier substrate arrangement 10 comprising a lowercarrier substrate 11 and an upper carrier substrate 12. At its top 13,the lower carrier substrate 11 comprises a connector arrangement 14which in the case shown comprises a conductor path structure formed onthe top 13 by means of the deposit method. In the present case, thecarrier substrate 11 and the carrier substrate 12 comprise polyamide;however, in principle, in the method explained below, other dielectricmaterials can also be used for the carrier substrates. In the presentcase, copper or a copper alloy is used for the connector arrangement 14.

[0033] The carrier substrate 12, which is arranged on the carriersubstrate 11 or on the connector arrangement 14 of the carrier substrate11, comprises substrate recesses 15 which extend as through-holes fromthe top 18 of the carrier substrate 12 to the underside 19 of thecarrier substrate 12, wherein the substrate recesses 15 in downwarddirection are delimited by the connector arrangement 14 which thus formsthe bottom 20 of the substrate recesses 15. Arranged at the top 18 ofthe carrier substrate 12 is a further connector arrangement 21 which isarranged such that it extends at least in part around an upper aperturemargin 22 of the substrate recesses 15. The connector arrangement 21 canbe connected so as to adhere, for example in an integral manner, to thetop 18 of the carrier substrate 12, or it can be formed independently ofthe carrier substrate 12, thus lying loosely on the top 18 of thecarrier substrate 12.

[0034] In order to carry out the method which is explained in moredetail below, as shown in FIGS. 1, 2 and 3, the carrier substratearrangement 10 rests against a supporting base 23.

[0035] As shown in FIG. 2, subsequently, in a first method-related step,a formed solder material part 24 is placed on each substrate recess 15.As shown in an exemplary way in FIG. 2, for this purpose the carriersubstrate arrangement 10 is moved in the direction of feed 49, at aclocked speed, past a component placement device 25 by means of a base23, which in the present case is a conveyor device. In the subsequentmethod-related step, a forming process of the formed solder materialpart 24 to form a formed contact part 50 takes place by means of amechanical forming device 26, wherein the base 23 serves as a backstopfor accommodating a forming force 27. The formed contact part 50provides through-plating of the carrier substrate 12 between theconnector arrangements 14 and 21. The forming force 27 results in aradial displacement of solder material of the formed solder materialpart 24, in the present case said radial displacement being delimited byan intrados surface 28 which is a cylinder jacket. Due to the plasticdeformation of the solder material, the forming force 27 has a radialeffect on the intrados surface 28 even after completion of the formingprocess. Furthermore, due to the larger material volume of the formedsolder material part 24 when compared to the lumen of the substraterecess 15, as a result of the forming process, a contact head 29 formsat the upper end of the formed contact part 50, as shown in the exampleof the substrate recess 15 on the left in FIG. 2. Due to the formingprocess, the formed contact part 50 comprises a radial overhang 30 whichin the region of the aperture margin 22 extends over an associatedmargin area 31 of the connector arrangement 21. It should be stressedthat the radial overhang 30 is not necessary for generating a holdingforce acting between the connector arrangement 21 and the carriersubstrate 12. The radially acting circumferential force which istransferred from the formed contact part 50 to the intrados surface 28and a corresponding intrados surface 32 of the connector arrangement 21is quite sufficient for this purpose. Only in the case where theconnector arrangement 21 does not extend over a partial circumference ofthe aperture margin 22, which partial circumference is adequate forgenerating the holding force, is it necessary, in the case of aconnector arrangement 21, which is arranged so as to be loose on the top18 of the carrier substrate 12, to form a contact head 29 with overhang30. Otherwise, forming a contact head without overhang is adequate, withsaid contact head being designed to be essentially flush in relation tothe circumferential area of the formed contact part 50.

[0036]FIG. 3 shows the option of applying and subsequently re-melting,in a subsequent further method-related step, a further formed soldermaterial part 51 which can be identical to or different from the formedsolder material part 24, onto a contact surface 56 of the contact head29 of the formed contact part 50 which is arranged in the substraterecess 15, by means of a component placement device 33 which can be of adesign that is comparable or identical to that of the componentplacement device 25. As further shown in FIG. 3, the re-melting processresults in the formation of a solder bump 53 which establishesthrough-plating, with a meniscus-shaped raised contact 35 on the formedcontact part 50. As is further shown in FIG. 3, as a result of thesurface tension of the liquefied solder material, the overhang 30 of thecontact head 29, which overhang 30 was formed on the formed contact part50 because of the mechanical forming process (FIG. 2), can recede.

[0037] Depending on the type of exposure to thermal energy by the formedsolder material part 34 during the re-melting process, and depending onthe type of material selected for the solder material part 34, meltingof the entire formed solder material mass formed by the formed contactparts 50 and the formed solder parts 34 can take place, or melting ofthe formed solder material part 34 alone can take place.

[0038]FIGS. 4 and 5 show a contact substrate 37 (FIG. 4) and a contactsubstrate 38 (FIG. 5) which comprise a corresponding carrier substratearrangement 39. In each case, the carrier substrate arrangement 39comprises a carrier substrate 40 which on its underside 41 comprises aconnector arrangement 42 which is arranged so as to adhere to thecarrier substrate 40. Furthermore, the carrier substrate 40 comprises asubstrate recess 43 which extends from a top 44 to a reverse side 45 ofthe connector arrangement 42. On the top 44 of the carrier substrate 40,a further connector arrangement 46 is provided which is formedindependently of the carrier substrate 40.

[0039] For electrically conductive connection of the connectorarrangements 42 and 46 and at the same time for mechanical securing ofthe connector arrangement 46 on the top 44 of the carrier substrate 40,a formed contact part 47 comprising a flat contact head 48 (FIG. 4) ofthe type of the formed contact part 50 shown in FIG. 2 is formed at thecontact substrate 37. The contact head 48 comprises a flat contactsurface 57.

[0040] As FIG. 5 shows in comparison to this, in the case of contactsubstrate 38, by re-melting the formed contact part 47, instead of aflat contact head 48 (FIG. 4,) it is possible to provide ameniscus-shaped raised contact 54 for generating a solder bump 55 asthrough-plating.

[0041] In the manufacture of a contact substrate 62 as shown in FIG. 6,after placement of a formed solder material part 63 into a substraterecess 64, exposure of the formed solder material part 63 to pressuretakes place with a pressure stamp 58, such that as a result of a convexshaped contact surface 59 of the pressure stamp, a concave contactsurface 65 is generated in a formed contact part 66. At the same time, araised margin 60 of the formed contact part 66 arises, which margin 60covers at least one intrados surface 67 of an upper connectorarrangement 68. A centering device 69 formed in the contact surface 59of the pressure stamp 58 ensures that the margin 60 is formed evenly.

[0042]FIG. 7 shows the formed contact part 66 after a re-melting processwith a meniscus margin 71, which due to wetting of the connectorarrangement 68 now both axially and radially protrudes beyond anaperture margin 70 of the connector arrangement 68.

1. A method for producing a contact substrate with through-platingbetween a connector arrangement arranged at the top of a dielectriccarrier substrate and the underside of the carrier substrate, whereinthe connector arrangement extends along an aperture margin of asubstrate recess, and the underside of the carrier substrate issupported by a backstop, characterized in that a formed solder materialpart (24, 51) is placed in the substrate recess (15, 43), and in asubsequent method-related step said formed solder material part isdeformed within the substrate recess so as to form a formed contact part(47, 50), such that radial displacement of the material of the formedsolder material part in the substrate recess results in a non-positiveconnection between an intrados surface (28) of the substrate recess andthe connector arrangement (21, 46), and that the formed contact partprovides through-plating between the connector arrangement and theunderside (19, 41) of the carrier substrate.
 2. The method according toclaim 1, characterized in that radial displacement of the material ofthe formed solder material part (24, 51) takes place by forming adisc-shaped contact head (29, 48) which protrudes both axially andradially beyond the aperture margin (22), with the connector arrangementbeing accommodated in the region of the aperture margin between thecontact head and the top (18, 44) of the carrier substrate (12, 40). 3.The method according to claim 1, characterized in that radialdisplacement of the material of the formed solder material part (24, 51)takes place by means of a pressure stamp (58) with a convex contactsurface (59), such that, apart from radial displacement, axialdisplacement of the material against the direction of pressure of thepressure stamp is caused too.
 4. The method according to claim 3,characterized in that exposure to pressure takes place by means of apressure stamp (58) which on its contact surface (59) comprises acentering device (61).
 5. The method according to any one of claims 1 to4, characterized in that in a subsequent method-related step, thematerial of the formed contact part (42, 50, 52) is at least partlyre-melted.
 6. The method according to claim 5, characterized in thatre-melting takes place by means of laser energy.
 7. The method accordingto any one of the preceding claims, characterized in that prior toplacing the formed solder material part (24) into the substrate recess(15), a second connector arrangement (14) is arranged on the underside(19) of the carrier substrate, between the carrier substrate (12) andthe backstop (23), such that the second connector arrangement at leastin part forms a bottom (20) of the substrate recess.
 8. The methodaccording to any one of claims 1 to 6, characterized in that prior toplacing the formed solder material part into the substrate recess, onthe underside of the carrier substrate between the carrier substrate andthe backstop a second connector arrangement is arranged, such that thesecond connector arrangement extends along a lower aperture margin ofthe substrate recess.
 9. The method according to claim 7 or 8,characterized in that the second connector arrangement (14) is arrangedon a further carrier substrate (11).
 10. The method according to any oneof the preceding claims, characterized in that prior to re-melting ontothe contact head (29) the formed contact part (50) which is arranged inthe substrate recess (15), a further formed solder material part (34) isapplied, and subsequently the solder material is, at least in part,re-melted.
 11. The method according to claim 10, characterized in thatre-melting is carried out via laser energy.
 12. A contact substrate withthrough-plating, comprising a carrier substrate and a conductor pathstructure arranged on the carrier substrate, wherein the conductor pathstructure comprises a first connector arrangement which is arranged onthe underside of the carrier substrate, and a second connectorarrangement which is arranged on the top of the carrier substrate, andwherein a substrate recess extends between the connector arrangements,such that the lower connector arrangement at least in part forms abottom of the substrate recess, and the upper connector arrangementextends at least in part over the aperture margin of the substraterecess, characterized in that through-plating between the lowerconnector arrangement (14, 42) and the upper connector arrangement (21,46) is formed by way of a formed contact part (47, 50, 52), such thatthe formed contact part completely fills up the substrate recess (15,43), and the end of the formed contact part, which end is situatedopposite the bottom (20) of the substrate recess, comprises a contacthead (29, 48) which protrudes beyond the aperture margin (22) bothaxially and radially, with said contact head (29, 48) beingnon-positively connected with the upper connector arrangement.
 13. Thecontact substrate according to claim 12, characterized in that thecontact head (29, 48) is disc-shaped and comprises an essentially flatcontact surface (56, 57) which extends parallel to the surface of thecarrier substrate (12, 40).
 14. The contact substrate according to claim12, characterized in that the contact head is a meniscus-shaped raisedcontact (54).
 15. A contact substrate with through-plating, comprising acarrier substrate and a conductor path structure arranged on the carriersubstrate, wherein the conductor path structure comprises a firstconnector arrangement which is arranged on the underside of the carriersubstrate, and a second connector arrangement which is arranged on thetop of the carrier substrate, and wherein a substrate recess extendsbetween the connector arrangements, such that the lower connectorarrangement at least in part forms a bottom of the substrate recess, andthe upper connector arrangement extends at least in part around anaperture margin of the substrate recess, characterized in thatthrough-plating between the lower connector arrangement (14, 42) and theupper connector arrangement (21, 46) is formed by way of a formedcontact part (47, 50, 52), such that the end of the formed contact part,which end is situated opposite the bottom (20) of the substrate recess,comprises a concave contact surface with a raised contact margin whichis non-positively connected with the upper connector arrangement. 16.The contact substrate according to one of claims 12 to 15, characterizedin that the lower conductor part arrangement (14) is arranged on afurther carrier substrate (12).